Conventionally, as a current sensor that measures a DC current, namely a direct current and an AC current, namely an alternating current flowing through a conductor, a flux gate current sensor of (for example, refer to Patent Literature 1) and a hall element current sensor are known.
Although being capable of high precision measurement, the flux gate current sensor has a problem in that, because a core with an exciting coil wound therearound has to be magnetically saturated with an AC current, the excitation current increases and power consumption is large. In addition, in order to measure an AC current at a frequency exceeding several kHz, the excitation frequency has to become high; however, as the excitation frequency becomes high, the impedance of the exciting coil increases and a high voltage is required to flow a current for magnetic saturation of the core. Accordingly, another problem is that, because a large scale power supply is required as an AC (alternating current) excitation power supply and thus the flux gate current sensor is not capable of raising the excitation frequency, measurement at high frequencies is not possible.
In the meanwhile, although being capable of measuring from DC (direct current) up to approximately 100 kHz, the hall element current sensor has problems such as a change due to the temperature of a bias voltage of a hall element and have been unsuitable for high precision measurement.